The 8330 has 50% more available memory, a camera, and will have an OS 5.0 release. The 8830 doesn't have enough memory for OS 5.0 and won't be supported. I don't know if Telus blocks the GPS or not. The 8330 is still a supported phone; the 8830 has been replaced by the 9630. That should help you decide.
Posted from my CrackBerry at wapforums.crackberry.com
From a hardware perspective the 8830 is much better; just a more solid, professional unit. It is also a world phone (also works on GSM networks). The Curve has more memory, a camera, and will run OS 5.0.
For a business phone, I'd take the 8830. Better yet, see if they'll get you a Tour